Ellipticine induces apoptosis through p53-dependent pathway in human hepatocellular carcinoma HepG2 cells

Ellipticine targets FGFR3 to mediate the RAS/MAPK-P38 signalling pathway to induce apoptosis in hepatocellular carcinoma cells

This study aimed to investigate the toxic effects of ellipticine on liver cancer cells and predict its anti-liver cancer mechanism through network pharmacology, especially by targeting FGFR3 to regulate the RAS/MAPK-P38 signaling pathway, thereby inducing apoptosis of liver cancer cells. The inhibitory effect of ellipticine on the proliferation of HepG2, Huh-7, SMMC7721, BEL-7402, SK-HEP-1, LX-2, and MHCC97H cells was detected by CCK-8 assay, and the IC50 value was calculated. The potential targets of ellipticine were predicted by the database, and the intersection analysis with liver cancer-related targets was performed to construct a protein interaction network (PPI), (KEGG) pathway enrichment analysis, and molecular docking verification. FGFR3 in HepG2 cells was knocked down by siRNA, and the effects on cell proliferation, apoptosis, and ROS levels were observed. The expression changes of FGFR3, RAS, P38, and their phosphorylated forms after ellipticine treatment, as well as the effects of RAS agonist ML-908 and P38 inhibitor PD169316 on cell proliferation, apoptosis, and migration, were detected by Western blotting. Ellipticine has an inhibitory effect on all tested liver cancer cell lines, among which HepG2 has the strongest inhibitory effect, with an IC50 of 5.15 ± 0.25 μM. Ellipticine is predicted to have 32 potential targets, and 5 common targets among the 225 targets related to liver cancer, including PDGFRA, KIT, FGFR3, ERBB2, and STAT3. KEGG analysis showed that these targets are mainly involved in cancer pathways. Molecular docking showed that Ellipticine can bind strongly to FGFR3. FGFR3 expression is highest in HepG2 cells. After knocking down FGFR3, the proliferation ability of HepG2 cells is further weakened, and the addition of apoptosis inhibitor ZVAD can partially restore the proliferation ability. ROS levels increase after Ellipticine treatment, and ROS levels further increase after knocking down FGFR3, and ZVAD treatment can reduce ROS levels. After Ellipticine treatment, the expression levels of FGFR3, RAS, and p-P38 decrease. Ellipticine-induced cell proliferation inhibition and apoptosis were reversed by RAS agonist ML-908, whereas P38 inhibitor PD169316 exacerbated cell apoptosis and migration inhibition. Ellipticine induces apoptosis of liver cancer cells by targeting FGFR3 and inhibiting the RAS/MAPK-P38 signaling pathway. This discovery provides new mechanistic insights into Ellipticine as a liver cancer treatment and may lay the foundation for the development of targeted therapeutic strategies.

Bioactivities and Action Mechanisms of Ellipticine Derivatives Reported Prior to 2023

Currently, natural products are one of the priceless options for finding novel chemical pharmaceutical entities. Ellipticine is a naturally occurring alkaloid isolated from the leaves of Ochrosia elliptica Labill. Ellipticine and its derivatives are characterized by multiple biological activities. The purpose of this review was to provide a critical and systematic assessment of ellipticine and its derivatives as bioactive molecules over the last 60 years. Publications focused mainly on the total synthesis of alkaloids of this type without any evaluation of bioactivity have been excluded. We have reviewed papers dealing with the synthesis, bioactivity evaluation and mechanism of action of ellipticine and its derivatives. It was found that ellipticine and its derivatives showed cytotoxicity, antimicrobial ability, and anti-inflammatory activity, among which cytotoxicity toward cancer cell lines was the most investigated aspect. The inhibition of DNA topoisomerase II was the most relevant mechanism for cytotoxicity. The PI3K/AKT pathway, p53 pathway, and MAPK pathway were also closely related to the antiproliferative ability of these compounds. In addition, the structure-activity relationship was deduced, and future prospects were outlined. We are confident that these findings will lay a scientific foundation for ellipticine-based drug development, especially for anticancer agents.

Transition of amyloid/mutant p53 from tumor suppressor to an oncogene and therapeutic approaches to ameliorate metastasis and cancer stemness

The tumor suppressor p53 when undergoes amyloid formation confers several gain-of-function (GOF) activities that affect molecular pathways crucial for tumorigenesis and progression like some of the p53 mutants. Even after successful cancer treatment, metastasis and recurrence can result in poor survival rates. The major cause of recurrence is mainly the remnant cancer cells with stem cell-like properties, which are resistant to any chemotherapy treatment. Several studies have demonstrated the role of p53 mutants in exacerbating cancer stemness properties and epithelial-mesenchymal transition in these remnant cancer cells. Analyzing the amyloid/mutant p53-mediated signaling pathways that trigger metastasis, relapse or chemoresistance may be helpful for the development of novel or improved individualized treatment plans. In this review, we discuss the changes in the metabolic pathways such as mevalonate pathway and different signaling pathways such as TGF-β, PI3K/AKT/mTOR, NF-κB and Wnt due to p53 amyloid formation, or mutation. In addition to this, we have discussed the role of the regulatory microRNAs and lncRNAs linked with the mutant or amyloid p53 in human malignancies. Such changes promote tumor spread, potential recurrence, and stemness. Importantly, this review discusses the cancer therapies that target either mutant or amyloid p53, restore wild-type functions, and exploit the synthetic lethal interactions with mutant p53.

Nucleolar Stress Response via Ribosomal Protein L11 Regulates Topoisomerase Inhibitor Sensitivity of P53-Intact Cancers

Nucleolar stress response is caused by perturbations in ribosome biogenesis, induced by the inhibition of ribosomal RNA processing and synthesis, as well as ribosome assembly. This response induces p53 stabilization and activation via ribosomal protein L11 (RPL11), suppressing tumor progression. However, anticancer agents that kill cells via this mechanism, and their relationship with the therapeutic efficiency of these agents, remain largely unknown. Here, we sought to investigate whether topoisomerase inhibitors can induce nucleolar stress response as they reportedly block ribosomal RNA transcription. Using rhabdomyosarcoma and rhabdoid tumor cell lines that are sensitive to the nucleolar stress response, we evaluated whether nucleolar stress response is associated with sensitivity to topoisomerase inhibitors ellipticine, doxorubicin, etoposide, topotecan, and anthracyclines. Cell proliferation assay indicated that small interfering RNA-mediated RPL11 depletion resulted in decreased sensitivity to topoisomerase inhibitors. Furthermore, the expression of p53 and its downstream target proteins via western blotting showed the suppression of p53 pathway activation upon RPL11 knockdown. These results suggest that the sensitivity of cancer cells to topoisomerase inhibitors is regulated by RPL11-mediated nucleolar stress responses. Thus, RPL11 expression may contribute to the prediction of the therapeutic efficacy of topoisomerase inhibitors and increase their therapeutic effect of topoisomerase inhibitors.

The potential mechanism of Chebulae Fructus in the treatment of hepatocellular carcinoma on the basis of network pharmacology

INTRODUCTION AND OBJECTIVES

Hepatocellular carcinoma (HCC) ranks third on the list of the leading cause for cancer death globally. The treatment of HCC patients is unsatisfactory. However, the traditional Chinese medicine Chebulae Fructus has potential efficacy in the treatment of HCC.

MATERIALS AND METHODS

We mined the active ingredients of Chebulae Fructus and its main targets from the Traditional Chinese Medicine Systems Pharmacology database. HCC-related datasets were downloaded from The Cancer Genome Atlas database and differentially expressed genes (DEGs) in HCC were obtained by differential expression analysis. Top10 small molecule compounds capable of reversing HCC pathology were screened by the Connectivity Map database based on DEGs. Ellipticine, an extract of Chebulae Fructus, had the potential to reverse HCC pathology. Protein-Protein Interaction (PPI) networks of DEGs in HCC were constructed using STRING. Eighteen potential targets of Chebulae Fructus for the treatment of HCC were obtained by taking intersection of DEGs in HCC with targets corresponding to the active constituents of Chebulae Fructus. In addition, MTT assay was also employed to examine the effect of ellipticine on HCC cell viability.

RESULTS

It has been shown that ellipticine and ellagic acid have antitumor activity. Random Walk with Restart analysis of PPI networks was performed using potential targets as seeds, and the genes with the top 50 affinity coefficients were selected to construct a drug-active constituent-gene interaction network. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses of key genes involved in the treatment of HCC with Chebulae Fructus demonstrated that these genes were mainly enriched in signaling pathways related to tumor metabolism such as cAMP signaling pathway and Ras signaling pathway. Finally, it was verified by MTT assay that proliferation of HCC cells could be remarkably hindered.

CONCLUSIONS

We excavated ellipticine, a key active constituent of Chebulae Fructus, by network pharmacology, and elucidated the signaling pathways involved in Chebulae Fructus, providing a theoretical basis for the use of Chebulae Fructus for HCC clinical application.

A Review on Mechanistic Insight of Plant Derived Anticancer Bioactive Phytocompounds and Their Structure Activity Relationship

Cancer is a disorder that rigorously affects the human population worldwide. There is a steady demand for new remedies to both treat and prevent this life-threatening sickness due to toxicities, drug resistance and therapeutic failures in current conventional therapies. Researchers around the world are drawing their attention towards compounds of natural origin. For decades, human beings have been using the flora of the world as a source of cancer chemotherapeutic agents. Currently, clinically approved anticancer compounds are vincristine, vinblastine, taxanes, and podophyllotoxin, all of which come from natural sources. With the triumph of these compounds that have been developed into staple drug products for most cancer therapies, new technologies are now appearing to search for novel biomolecules with anticancer activities. Ellipticine, camptothecin, combretastatin, curcumin, homoharringtonine and others are plant derived bioactive phytocompounds with potential anticancer properties. Researchers have improved the field further through the use of advanced analytical chemistry and computational tools of analysis. The investigation of new strategies for administration such as nanotechnology may enable the development of the phytocompounds as drug products. These technologies have enhanced the anticancer potential of plant-derived drugs with the aim of site-directed drug delivery, enhanced bioavailability, and reduced toxicity. This review discusses mechanistic insights into anticancer compounds of natural origins and their structural activity relationships that make them targets for anticancer treatments.

Paradoxical Pro-angiogenic Effect of Low-Dose Ellipticine Identified by In Silico Drug Repurposing

Inadequate vessel maintenance or growth causes ischemia in diseases such as myocardial infarction, stroke, and neurodegenerative disorders. Therefore, developing an effective strategy to salvage ischemic tissues using a novel compound is urgent. Drug repurposing has become a widely used method that can make drug discovery more efficient and less expensive. Additionally, computational virtual screening tools make drug discovery faster and more accurate. This study found a novel drug candidate for pro-angiogenesis by in silico virtual screening. Using Gene Expression Omnibus (GEO) microarray datasets related to angiogenesis studies, differentially expressed genes were identified and characteristic direction signatures extracted from GEO2EnrichR were used as input data on L1000CDS² to screen pro-angiogenic molecules. After a thorough review of the candidates, a list of compounds structurally similar to TWS-119 was generated using ChemMine Tools and its clustering toolbox. ChemMine Tools and ChemminR structural similarity search tools for small-molecule analysis and clustering were used for second screening. A molecular docking simulation was conducted using AutoDock v.4 to evaluate the physicochemical effect of secondary-screened chemicals. A cell viability or toxicity test was performed to determine the proper dose of the final candidate, ellipticine. As a result, we found ellipticine, which has pro-angiogenic effects, using virtual computational methods. The noncytotoxic concentration of ellipticine was 156.25 nM. The phosphorylation of glycogen synthase kinase-3β was decreased, whereas the β-catenin expression was increased in human endothelial cells treated with ellipticine. We concluded that ellipticine at sublethal dosage could be successfully repositioned as a pro-angiogenic substance by in silico virtual screening.

Anticancer potential of myricetin bulk and nano forms in vitro in lymphocytes from myeloma patients

Evading apoptosis and chemo-resistance are considered as very important factors which help tumour progression and metastasis. Hence, to overcome chemo-resistance, there is an urgent requirement for emergence of more effective treatment options. Myricetin, a naturally occurring flavonoid, is present in various plant-derived foods and shows antitumour potential in different cancers. In the present in vitro study, results from the comet assay demonstrated that myricetin bulk (10 µM) and nano (20 µM) forms exhibited a non-significant level of genotoxicity in lymphocytes from multiple myeloma patients when compared to those from healthy individuals. Western blot results showed a decrease in Bcl-2/Bax ratio and an increase in P53 protein levels in lymphocytes from myeloma patients, but not in lymphocytes from healthy individuals. A significant increase in intracellular reactive oxygen species level was also observed, suggesting that regulation of apoptotic proteins triggered by myricetin exposure in lymphocytes from myeloma patients occurred through P53 and oxidative stress-dependent pathways. The potency of myricetin against lymphocytes from myeloma patients marks it a potential candidate to be considered as an alternative to overcome chemo-resistance in cancer therapies.

Identification of candidate biomarkers and therapeutic drugs of colorectal cancer by integrated bioinformatics analysis

Most colorectal cancer (CRC) patients are diagnosed with advanced stages and low prognosis. We aimed to identify potential diagnostic and prognostic biomarkers, as well as active small molecules of CRC. Microarray data (GSE9348, GSE35279, and GSE106582) were obtained from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were identified by the GEO2R platform. Common DEGs were selected for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Cytoscape software was used to construct protein-protein interaction networks and identify hub genes. Hub genes were evaluated by Kaplan-Meier survival analysis in the GEPIA database and validated in two independent microarray data (GSE74602 and GSE83889). Common DEGs were used to select active small molecules by the connectivity map database. A total of 166 DEGs were identified as common DEGs. GO analysis demonstrated that common DEGs were significantly enriched in the apoptotic process, cell proliferation, and cell adhesion. KEGG analysis indicated that the most enriched pathways were the PI3K-Akt signaling pathway and extracellular matrix-receptor interaction. COL1A2, THBS2, TIMP1, and CXCL8 significantly upregulated in colorectal tumor. High expressions of COL1A2, THBS2, and TIMP1 were associated with poor survival, while high expressions of CXCL8 were associated with better survival. We selected 11 small molecules for CRC therapy. In conclusion, we found key dysregulated genes associated with CRC and potential small molecules to reverse them. COL1A2, THBS2, TIMP1, and CXCL8 may act as diagnostic and prognostic biomarkers of CRC.

Galangin, a Flavonoid from Lesser Galangal, Induced Apoptosis via p53-Dependent Pathway in Ovarian Cancer Cells

Among women worldwide, ovarian cancer is one of the most dangerous cancers. Patients undergoing platinum-based chemotherapy might get adverse side effects and develop resistance to drugs. In recent years, natural compounds have aroused growing attention in cancer treatment. Galangin inhibited the growth of two cell lines, A2780/CP70 and OVCAR-3, more strongly than the growth of a normal ovarian cell line, IOSE 364. The IC₅₀ values of galangin on proliferation of A2780/CP70, OVCAR-3 and IOSE 364 cells were 42.3, 34.5, and 131.3 μM, respectively. Flow cytometry analysis indicated that galangin preferentially induced apoptosis in both ovarian cancer cells with respect to normal ovarian cells. Galangin treatment increased the level of cleaved caspase-3 and -7 via the p53-dependent intrinsic apoptotic pathway by up-regulating Bax protein and via the p53-dependent extrinsic apoptotic pathway by up-regulating DR5 protein. By down-regulating the level of p53 with 20 μM pifithrin-α (PFT-α), the apoptotic rates of OVCAR-3 cells induced by galangin treatment (40 μM) were significantly decreased from 18.2% to 10.2%, indicating that p53 is a key regulatory protein in galangin-induced apoptosis in ovarian cancer cells. Although galangin up-regulated the expression of p21, it had little effect on the cell cycle of the two ovarian cancer cell lines. Furthermore, the levels of phosphorylated Akt and phosphorylated p70S6K were decreased through galangin treatment, suggesting that the Akt/p70S6K pathways might be involved in the apoptosis. Our results suggested that galangin is selective against cancer cells and can be used for the treatment of platinum-resistant ovarian cancers in humans.

Small Molecules Targeting Mutant P53: A Promising Approach for Cancer Treatment

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More than half of all human tumors express mutant forms of p53, with the ovary, lung, pancreas, and colorectal cancers among the tumor types that display the highest prevalence of p53 mutations. In addition, the expression of mutant forms of p53 in tumors is associated with poor prognosis due to increased chemoresistance and invasiveness. Therefore, the pharmacological restoration of wild-type-like activity to mutant p53 arises as a promising therapeutic strategy against cancer. This review is focused on the most relevant mutant p53 small molecule reactivators described to date. Despite some of them have entered into clinical trials, none has reached the clinic, which emphasizes that new pharmacological alternatives, particularly with higher selectivity and lower adverse toxic side effects, are still required.

Cancer Chemotherapy by Novel Bio-active Natural Products: Looking Towards the Future

Background:

Cancer is the second leading cause of death globally and accounted for 8.8 million deaths annually in humans. Lung, prostate, colorectal, stomach and liver cancer are the most common types of cancer in men, while breast, colorectal, lung, cervix and stomach cancer are the most common among women. Numerous drugs that the US Food and Drug Administration (FDA) have approved for use in cancer therapy are derived from plants, including taxanes such as paclitaxel and vinca alkaloids such as vincristine and vinblastine. Still, there is an intense need for a search for numerous bioactive sources to develop a novel anti-cancer drug to overcome this chronic disorder. About more than thirty plants derived natural products have been isolated till date and are currently under clinical trials. As per literature survey from various journals and texts has been found to be novel medicinal agents from bioactive sources are clinically active against various types of cancer cells.

Conclusion:

Current review has been highlighted on the novel medicinal agents from plant sources have potential effects against many types of cancer, which have been supported by clinical trials. The main findings of these active novel medicinal agents were also summarized and discussed here.

Anticancer Activity of Natural Compounds from Plant and Marine Environment

This paper describes the substances of plant and marine origin that have anticancer properties. The chemical structure of the molecules of these substances, their properties, mechanisms of action, their structure⁻activity relationships, along with their anticancer properties and their potential as chemotherapeutic drugs are discussed in this paper. This paper presents natural substances from plants, animals, and their aquatic environments. These substances include the vinca alkaloids, mistletoe plant extracts, podophyllotoxin derivatives, taxanes, camptothecin, combretastatin, and others including geniposide, colchicine, artesunate, homoharringtonine, salvicine, ellipticine, roscovitine, maytanasin, tapsigargin, and bruceantin. Compounds (psammaplin, didemnin, dolastin, ecteinascidin, and halichondrin) isolated from the marine plants and animals such as microalgae, cyanobacteria, heterotrophic bacteria, invertebrates (e.g., sponges, tunicates, and soft corals) as well as certain other substances that have been tested on cells and experimental animals and used in human chemotherapy.

Awakening the "guardian of genome": reactivation of mutant p53

The role of tumor suppressor protein p53 is undeniable in the suppression of cancer upon oncogenic stress. It induces diverse conditions such as cell-cycle arrest, cell death, and senescence to protect the cell from carcinogenesis. The rate of mutations in p53 gene nearly accounts for 50% of the human cancers. Upon mutations, the conformation gets altered and becomes non-native. Mutant p53 displays long half-life and accumulates in the nucleus and interacts with oncoproteins to promote carcinogenesis and these interactions present a formidable challenge for clinicians in therapy of the disease. Variety of approaches have been developed, through which native-like function of p53 can be restored, such as restoration of the native-like structure of p53, activating the p53 family members, etc. Modern scientific techniques have led to the discovery of a variety of molecules to reactivate mutant p53 and restore its transcriptional activity. These compounds include small molecules, various peptides, and phytochemicals. In this review article, we comprehensively discuss these molecules to reactivate mutant p53 to restore the normal function with a particular focus on molecular mechanisms.

Ellipticine inhibits the proliferation and induces apoptosis in rheumatoid arthritis fibroblast-like synoviocytes via the STAT3 pathway

OBJECTIVE

Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) is an alkaloid isolated from Apocyanaceae plants. This study was designed to investigate the effects of ellipticine on the proliferation and apoptosis of fibroblast-like synoviocytes (FLSs) from patients with rheumatoid arthritis (RA).

METHODS

RA-FLSs were exposed to different concentrations of ellipticine (i.e., 0.5, 1, 2, 4 and 8 μM) for 24-72h and measured for viability, proliferation and apoptosis. The involvement of signal transducer and activators of transcription 3 (STAT3) signaling in the action of ellipticine was determined by Western blot analysis, luciferase reporter assay and rescue experiments.

RESULTS

Ellipticine treatment significantly inhibited the viability and proliferation of RA-FLSs in a concentration-dependent manner. In contrast, ellipticine exposure did not alter the viability of normal human FLSs. Moreover, ellipticine triggered significant apoptosis and increased caspase-3 activity in RA-FLSs. Mechanistically, ellipticine reduced the phosphorylation of STAT3 and downregulated the expression of Mcl-1, cyclin D1 and Bcl-2. Luciferase reporter assay demonstrated that ellipticine treatment led to a significant inhibition of STAT3-mediated transcriptional activity in RA-FLSs. Overexpression of constitutively active STAT3 reversed the suppressive effects of ellipticine on RA-FLSs, which was accompanied by restoration of Mcl-1, cyclin D1 and Bcl-2.

DISCUSSION AND CONCLUSIONS

Ellipticine shows anti-proliferative and pro-apoptotic effects on RA-FLSs through inhibition of the STAT3 pathway and may have therapeutic potential in RA.

ATM participates in the regulation of viability and cell cycle via ellipticine in bladder cancer

Ellipticine, an alkaloid isolated from Apocyanaceae plants, has been demonstrated to exhibit antitumor activity in several cancers. However, the effect and the mechanisms underlying its action have not been investigated in human bladder cancer cells. The aim of the present study was to investigate the effect and mechanism of ellipticine on the behavior of T-24 bladder cancer cells. T-24 cells were treated with varying concentrations and durations of ellipticine. Cell viability was evaluated by Cell Counting Kit-8 assay. Cell motility was analyzed by Transwell migration assay. Flow cytometry, reverse transcription-quantitative polymerase chain reaction and western blot analyses were performed to detect the cell cycle and signaling pathways involved. The results demonstrated that ellipticine suppressed proliferation and inhibited the migration ability of T-24 bladder cancer cells in a dose- and time-dependent manner, and resulted in G2/M cell cycle arrest. The mechanism of this action was demonstrated to be due to ellipticine-triggered activation of the ATM serine/threonine kinase pathway. These data therefore suggest that ellipticine may be effective towards treating human bladder cancer.

Theaflavin-3, 3'-digallate induces apoptosis and G2 cell cycle arrest through the Akt/MDM2/p53 pathway in cisplatin-resistant ovarian cancer A2780/CP70 cells

Ovarian cancer is the most lethal gynecological cancer among women worldwide. Adverse side effects and acquired resistance to conventional platinum based chemotherapy are major impediments in ovarian cancer treatment, and drive the development of more selective anticancer drugs that target cancer-specific defects. In this study, theaflavin-3, 3′-digallate (TF3), the major theaflavin monomer in black tea, exhibited a potent growth inhibitory effect on the cisplatin-resistant ovarian cancer A2780/CP70 cells (IC₅₀, 23.81 μM), and was less cytotoxic to a normal ovarian IOSE-364 cells (IC₅₀, 59.58 μM) than to the cancer cells. Flow cytometry analysis indicated that TF3 induced preferential apoptosis and G2 cell cycle arrest in A2780/CP70 cells with respect to IOSE-364 cells. TF3 induced apoptosis through both the intrinsic and extrinsic apoptotic pathways, and caused G2 cell cycle arrest via cyclin B1 in A2780/CP70 cells. The p53 protein played an important role in TF3-induced apoptosis and G2 cell cycle arrest. TF3 might upregulate the p53 expression via the Akt/MDM2 pathway. Our findings help elucidate the mechanisms by which TF3 may contribute to the prevention and treatment of platinum-resistant ovarian cancer.

3-(Dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (DPA-HBFQ-1) plays an inhibitory role on breast cancer cell growth and progression

A series of unknown 3-(alkyl(dialkyl)amino)benzofuro[2,3-f]quinazolin-1(2H)-ones 4-17 has been synthesized as new ellipticine analogs, in which the carbazole moiety and the pyridine ring were replaced by a dibenzofuran residue and a pyrimidine ring, respectively. The synthesis of these benzofuroquinazolinones 4-17 was performed in a simple one-pot reaction using 3-aminodibenzofuran or its 2-methoxy derivative, as starting materials. From 3-(dipropylamino)-5-methoxybenzofuro[2,3-f] quinazolin-1(2H)-one (13), we prepared 3-(dipropylamino)-5-hydroxybenzofuro[2,3-f]quinazolin-1(2H)-one (18), referred to as DPA-HBFQ-1. The cytotoxic activities of all the synthesized compounds, tested in different human breast cancer cell lines, revealed that DPA-HBFQ-1 was the most active compound. In particular, the latter was able to inhibit anchorage-dependent and -independent cell growth and to induce apoptosis in estrogen receptor alpha (ERα)-positive and -negative breast cancer cells. It did not affect proliferation and apoptotic responses in MCF-10A normal breast epithelial cells. The observed effects have been ascribed to an enhanced p21(Cip1/WAF1) expression in a p53-dependent manner of tumor suppressor and to a selective inhibition of human topoisomerase II. In addition, DPA-HBFQ-1 exerted growth inhibitory effects also in other cancer cell lines, even though with a lower cytotoxic activity. Our results indicate DPA-HBFQ-1 as a good candidate to be useful as cancer therapeutic agent, particularly for breast cancer.

Myricetin inhibits proliferation of cisplatin-resistant cancer cells through a p53-dependent apoptotic pathway

Cisplatin is a commonly used drug for cancer treatment by crosslinking DNA, leading to apoptosis of cancer cells, resistance to cisplatin treatment often occurs, leading to relapse. Therefore, there is a need for the development of more effective treatment strategies that can overcome chemoresistance. Myricetin is a flavonoid from fruits and vegetables, showing anticancer activity in various cancer cells. In this study, we found myricetin exhibited greater cytotoxicity than cisplatin in two cisplatin-resistant ovarian cancer cell lines, OVCAR-3 and A2780/CP70, and it was less cytotoxic to the normal ovarian cell line IOSE-364. Myricetin selectively induced apoptosis in both cisplatin-resistant cancer cell lines, but did not induce apoptosis in the normal ovarian cell line. It induced both Bcl-2 family-dependent intrinsic and DR5 dependent extrinsic apoptosis in OVCAR-3 cells. P53, a multifunctional tumor suppressor, regulated apoptosis in OVCAR-3 cells through a Bcl-2 family protein-dependent pathway. Myricetin did not induce cell cycle arrest in either ovarian cancer cell line. Because of its potency and selectivity against cisplatin-resistant cancer cells, myricetin could potentially be used to overcome cancer chemoresistance against platinum-based therapy.

Computer aided screening of natural compounds targeting the E6 protein of HPV using molecular docking

The cancer profile in the Indian state of Uttarakhand reveals that the breast cancer is the most prevalent type of cancers in females followed by cervical and ovarian type. Literature survey shows that the E6 protein of Human Papilloma Virus-16 (HPV-16) is responsible for causing several forms of cancer in human. Therefore, it is of interest to screen HPV-16 E6 target protein with known natural compounds using computer aided molecular modeling and docking tools. The complete structure of E6 is unknown. Hence, the E6 structure model was constructed using different online servers followed by molecular docking of Colchine, Curcumin, Daphnoretin, Ellipticine and Epigallocatechin-3-gallate; five known natural compounds with best E6 protein model predicted by Phyre2 server. The screening exercise shows that Daphnoretin (with binding free energy of -8.3 kcal/mol), a natural compound derived from Wikstroemia indica has the top binding properties. Thus, it is of interest to consider the compound for further validation.

The collective nuclear migration of p53 and phosphorylated S473 of Akt during ellipticine-mediated apoptosis in human lung epithelial cancer cells

Topoisomerase II inhibitor ellipticine effectively suppressed the growth of human non-small-cell-lung-cancer (NSCLC) epithelial cells. Previously, we reported the drug activity was consummated through parallel nucleus migration of p53 and Akt in A549 cells. While inducing cell death, the drug activity was proved related to autophagy through phosphorylated Akt at S473. In addition, ellipticine induced cytotoxicity in p53-null H1299 cells with stable expression of ectopic p53. In this work, we further demonstrated that dominant-negative Akt (S473A) or p53 shRNA inhibited ellipticine-mediated translocalization of p53 and Akt and attenuated apoptotic cell death in A549 cells. The presence of p53 predates ellipticine-mediated apoptotic cell death, assists in nucleus translocation of phosphorylated Akt and activation of autophagy pathway. Growth inhibition through collaborating p53 and phosphorylated Akt(473) in lung epithelial cancer cells provided a new perspective of the topoisomerase inhibitor as an effective cancer therapy agent.

The anticancer drug ellipticine activated with cytochrome P450 mediates DNA damage determining its pharmacological efficiencies: studies with rats, Hepatic Cytochrome P450 Reductase Null (HRN™) mice and pure enzymes

Ellipticine is a DNA-damaging agent acting as a prodrug whose pharmacological efficiencies and genotoxic side effects are dictated by activation with cytochrome P450 (CYP). Over the last decade we have gained extensive experience in using pure enzymes and various animal models that helped to identify CYPs metabolizing ellipticine. In this review we focus on comparison between the in vitro and in vivo studies and show a necessity of both approaches to obtain valid information on CYP enzymes contributing to ellipticine metabolism. Discrepancies were found between the CYP enzymes activating ellipticine to 13-hydroxy- and 12-hydroxyellipticine generating covalent DNA adducts and those detoxifying this drug to 9-hydroxy- and 7-hydroellipticine in vitro and in vivo. In vivo, formation of ellipticine-DNA adducts is dependent not only on expression levels of CYP3A, catalyzing ellipticine activation in vitro, but also on those of CYP1A that oxidize ellipticine in vitro mainly to the detoxification products. The finding showing that cytochrome b5 alters the ratio of ellipticine metabolites generated by CYP1A1/2 and 3A4 explained this paradox. Whereas the detoxification of ellipticine by CYP1A and 3A is either decreased or not changed by cytochrome b5, activation leading to ellipticine-DNA adducts increased considerably. We show that (I) the pharmacological effects of ellipticine mediated by covalent ellipticine-derived DNA adducts are dictated by expression levels of CYP1A, 3A and cytochrome b5, and its own potency to induce these enzymes in tumor tissues, (II) animal models, where levels of CYPs are either knocked out or induced are appropriate to identify CYPs metabolizing ellipticine in vivo, and (III) extrapolation from in vitro data to the situation in vivo is not always possible, confirming the need for these animal models.

Chaetoglobosin K induces apoptosis and G2 cell cycle arrest through p53-dependent pathway in cisplatin-resistant ovarian cancer cells

Adverse side effects and acquired resistance to conventional platinum based chemotherapy have become major impediments in ovarian cancer treatment, and drive the development of more selective anticancer drugs. Chaetoglobosin K (ChK) was shown to have a more potent growth inhibitory effect than cisplatin on two cisplatin-resistant ovarian cancer cell lines, OVCAR-3 and A2780/CP70, and was less cytotoxic to a normal ovarian cell line, IOSE-364, than to the cancer cell lines. Hoechst 33342 staining and Flow cytometry analysis indicated that ChK induced preferential apoptosis and G2 cell cycle arrest in both ovarian cancer cells with respect to the normal ovarian cells. ChK induced apoptosis through a p53-dependent caspase-8 activation extrinsic pathway, and caused G2 cell cycle arrest via cyclin B1 by increasing p53 expression and p38 phosphorylation in OVCAR-3 and A2780/CP70 cells. DR5 and p21 might play an important role in determining the sensitivity of normal and malignant ovarian cells to ChK. Based on these results, ChK would be a potential compound for treating platinum-resistant ovarian cancer.

Ellipticine induces apoptosis in T-cell lymphoma via oxidative DNA damage

The tumor suppressor p53 is often mutated in human cancers. Restoring its antitumor activity has been shown to be a promising therapeutic approach for cancer treatment. Here we analyzed the activity and mechanism of a p53 reactivator, ellipticine, in a cellular model of cutaneous T-cell lymphoma (CTCL), a disease that is progressive, chemoresistant and refractory to treatment. We tested the effect of ellipticine in three cell lines with different p53 status: MyLa2000 (p53(wt/wt)), SeAx ((G245S)p53) and Hut-78 ((R196Stop)p53). Ellipticine caused apoptosis in MyLa2000 and SeAx and restored the transcriptional activity of (G245S)p53 in SeAx. However, p53 siRNA knockdown experiments revealed that p53 was not required for ellipticine-induced apoptosis in CTCL. The lipophilic antioxidant α-tocopherol inhibited ellipticine-dependent apoptosis and we linked the apoptotic response to the oxidative DNA damage. Our results provide evidence that ellipticine-induced apoptosis is exerted through DNA damage and does not require p53 activation in T-cell lymphoma.

A Novel Anticancer Agent, 8-Methoxypyrimido[4',5':4,5]thieno(2,3-b) Quinoline-4(3H)-One Induces Neuro 2a Neuroblastoma Cell Death through p53-Dependent, Caspase-Dependent and -Independent Apoptotic Pathways

Neuroblastoma is the most common cancer in infants and fourth most common cancer in children. Despite recent advances in cancer treatments, the prognosis of stage-IV neuroblastoma patients continues to be dismal which warrant new pharmacotherapy. A novel tetracyclic condensed quinoline compound, 8-methoxypyrimido [4',5':4,5]thieno(2,3-b) quinoline-4(3H)-one (MPTQ) is a structural analogue of an anticancer drug ellipticine and has been reported to posses anticancer property. Study on MPTQ on neuroblastoma cells is very limited and mechanisms related to its cytotoxicity on neuroblastoma cells are completely unknown. Here, we evaluated the anticancer property of MPTQ on mouse neuro 2a and human SH-SY5Y neuroblastoma cells and investigated the mechanisms underlying MPTQ-mediated neuro 2a cell death. MPTQ-mediated neuro 2a and SH-SY5Y cell deaths were found to be dose and time dependent. Moreover, MPTQ induced cell death reached approximately 99.8% and 90% in neuro 2a and SH-SY5Y cells respectively. Nuclear oligonucleosomal DNA fragmentation and Terminal dUTP Nick End Labelling assays indicated MPTQ-mediated neuro 2a cell death involved apoptosis. MPTQ-mediated apoptosis is associated with increased phosphorylation of p53 at Ser15 and Ser20 which correlates with the hyperphosphorylation of Ataxia-Telangiectasia mutated protein (ATM). Immunocytochemical analysis demonstrated the increased level of Bax protein in MPTQ treated neuro 2a cells. MPTQ-mediated apoptosis is also associated with increased activation of caspase-9, -3 and -7 but not caspase-2 and -8. Furthermore, increased level of caspase-3 and cleaved Poly (ADP Ribose) polymerase were observed in the nucleus of MPTQ treated neuro 2a cells, suggesting the involvement of caspase-dependent intrinsic but not extrinsic apoptotic pathway. Increased nuclear translocation of apoptosis inducing factor suggests additional involvement of caspase-independent apoptosis pathway in MPTQ treated neuro 2a cells. Collectively, MPTQ-induced neuro 2a cell death is mediated by ATM and p53 activation, and Bax-mediated activation of caspase-dependent and caspase-independent mitochondrial apoptosis pathways.

Antioxidants: friends or foe in prevention or treatment of cancer: the debate of the century

There are a number of intrinsic (e.g. oncogenes) and extrinsic (e.g. radiation and inflammation) factors, which may arise in reactive oxygen species (ROS), resulting in DNA instability and then cancer. In this situation, initial cancerous cells would balance the harmful effects of ROS by switching on the protective effects in a longstanding manner. In normal conditions, ROS have an important role in signal transduction and gene transcription, nevertheless, ROS may act as a trigger for carcinogenesis via persistent DNA injuries as well as mutations in p53 such as conditions observed in skin, hepatocellular, and colon cancers. Some compounds like paclitaxel are able to attack cancer cells through generation of ROS or interfering with ROS metabolism, while there are a few anti-angiogenesis compounds without toxicity such as endostatin, which act as anti-neoplastic only together with another chemotherapeutic drug. Furthermore, some anti-cancer agents like piperlongumine bind to the active sites of several key cellular antioxidants including glutathione S transferase and carbonyl reductase 1 only in the cancer cells. Although the natural antioxidants can alone or in combination with the diet provide some benefits for chemoprevention, their position in cancer therapy, especially initial stages of carcinogenesis is breaking down. On the other hand antioxidants can promote the survival of detached cells from extra cellular medium playing dual activities with respect to tumorigenesis through inhibition of tumorigenesis by preventing oxidative injuries to DNA and otherwise maintenance of tumor by promoting cell survival via metabolic rescue. Hopefully, more details of antioxidant and anti-neoplastic mechanisms become clear day by day, which have made researchers renew the strategy for designing cancer prevention or treatment.

Novel Nitrobenzazolo[3,2-a]quinolinium Salts Induce Cell Death through a Mechanism Involving DNA Damage, Cell Cycle Changes, and Mitochondrial Permeabilization

This study reports the capacity of three nitro substituted benzazolo[3,2-a]quinolinium salts NBQs: NBQ 95 (NSC-763304), NBQ 38 (NSC 763305), and NBQ 97 (NSC-763306) as potential antitumor agents. NBQ's are unnatural alkaloids possessing a positive charge that could facilitate interaction with cell organelles. The anticancer activities of these compounds were evaluated through the National Cancer Institute (NCI) 60 cell line screening which represents diverse histologies. The screening was performed at 10 µM on all cell lines. Results from the NCI screening indicated cytotoxicity activity on six cell lines. In order to explore a possible mechanism of action, a detailed biological activity study of NBQ 95 and NBQ 38 was performed on A431 human epidermoid carcinoma cells to determine an apoptotic pathway involving, cell cycle changes, DNA fragmentation, mutations, mitochondrial membrane permeabilization and caspases activation. DNA fragmentation, cell cycle effects, mutagenesis, mitochondrial permeabilization and activation of caspases were determined by fluorimetry and differential imaging. Our data showed that A431 growth was inhibited with an average IC50 of 30 µM. In terms of the mechanism, these compounds interacted with DNA causing fragmentation and cell cycle arrest at sub G0/G1 stage. Mutagenesis was higher for NBQ 38 and moderate for NBQ 95 Mitochon-drial permeabilization was observed with NBQ 38 and slightly for NBQ 95. Both compounds caused activation of Caspases 3 and 7 suggesting an apoptotic cell death pathway through an intrinsic mechanism. This study reports evidence of the toxicity of these novel compounds with overlapping structural and mechanistic similarities to ellipticine, a known anti-tumor compound.

Old drug, new target: ellipticines selectively inhibit RNA polymerase I transcription

Transcription by RNA polymerase I (Pol-I) is the main driving force behind ribosome biogenesis, a fundamental cellular process that requires the coordinated transcription of all three nuclear polymerases. Increased Pol-I transcription and the concurrent increase in ribosome biogenesis has been linked to the high rates of proliferation in cancers. The ellipticine family contains a number of potent anticancer therapeutic agents, some having progressed to stage I and II clinical trials; however, the mechanism by which many of the compounds work remains unclear. It has long been thought that inhibition of Top2 is the main reason behind the drugs antiproliferative effects. Here we report that a number of the ellipticines, including 9-hydroxyellipticine, are potent and specific inhibitors of Pol-I transcription, with IC(50) in vitro and in cells in the nanomolar range. Essentially, the drugs did not affect Pol-II and Pol-III transcription, demonstrating a high selectivity. We have shown that Pol-I inhibition occurs by a p53-, ATM/ATR-, and Top2-independent mechanism. We discovered that the drug influences the assembly and stability of preinitiation complexes by targeting the interaction between promoter recognition factor SL1 and the rRNA promoter. Our findings will have an impact on the design and development of novel therapeutic agents specifically targeting ribosome biogenesis.

Pharmacokinetics of peptide mediated delivery of anticancer drug ellipticine

The amino acid pairing peptide EAK16-II (EAK) has shown the ability to stabilize the hydrophobic anticancer agent ellipticine (EPT) in aqueous solution. In this study, we investigate pharmacokinetics of the formulation of EAK-EPT complexes in vivo. The developed formulation can achieve a sufficiently high drug concentration required in vivo animal models. The nanostructure and surface properties of EAK-EPT complexes or nanoparticle were characterized by transmission electron microscopy (TEM) and zeta potential measurements, respectively. 12 healthy male SD rats were divided into EPT group and EAK-EPT group randomly. Rats in EPT group were tail intravenously injected with the EPT (20 mg/kg); rats in EAK-EPT group were injected with EAK-EPT complexes (EPT's concentration is 20 mg/kg). EPT was extracted from rat plasma with dexamethasone sodium phosphate as internal standards (IS). The pharmacokinetic parameters were obtained using high pressure liquid chromatography (HPLC). Significant differences in main pharmacokinetic parameters between EPT and EAK-EPT complexes were observed, demonstrating that the complexation with EAK prolongs the residence time of the drug and enlarges the area under the concentration-time curve (AUC). This means that EAK can serve as a suitable carrier to increase the bioavailability of EPT.

Ellipticine oxidation and DNA adduct formation in human hepatocytes is catalyzed by human cytochromes P450 and enhanced by cytochrome b5

Ellipticine is an antineoplastic agent considered a pro-drug, the pharmacological and genotoxic effects of which are dependent on cytochrome P450 (CYP)- and/or peroxidase-mediated activation to covalent DNA adducts. We investigated whether ellipticine-DNA adducts are formed in human hepatic microsomes and human hepatocytes. We then identified which human CYPs oxidize ellipticine to metabolites forming DNA adducts and the effect of cytochrome b(5) on this oxidation. 13-Hydroxyellipticine, the metabolite forming the major ellipticine-DNA adduct, was generated mainly by CYP3A4 and 1A1, followed by CYP2D6>2C19>1B1>1A2>2E1 and >2C9. Cytochrome b(5) increased formation of this metabolite by human CYPs, predominantly by CYP1A1, 3A4, 1A2 and 2C19. Formation of 12-hydroxyellipticine is generated mainly by CYP2C19, followed by CYP2C9>3A4>2D6>2E1 and >2A6. Other CYPs were less active (CYP2C8 and 2B6) or did not oxidize ellipticine to this metabolite (CYP1A1, 1A2 and 1B1). CYP2D6 was the most efficient enzyme generating ellipticine N(2)-oxide. CYP3A4 and 1A1 in the presence of cytochrome b(5) are mainly responsible for bioactivation of ellipticine to DNA adduct 1 (formed by ellipticine-13-ylium from 13-hydroxyellipticine), while 12-hydroxyellipticine generated during the CYP2C19-mediated ellipticine oxidation is the predominant metabolite forming ellipticine-12-ylium that generates ellipticine-DNA adduct 2. These ellipticine-DNA adducts were also generated by human hepatic microsomes and in primary human hepatocytes exposed to ellipticine. Ellipticine is toxic to these hepatocytes, decreasing their viability; the IC(50) value of ellipticine in these cells was 0.7 μM. In liver CYP3A4 is the predominant ellipticine activating CYP species, which is expected to result in efficient metabolism after oral ingestion of ellipticine in humans.

Paeoniflorin inhibits growth of human colorectal carcinoma HT 29 cells in vitro and in vivo

The aim of the therapy of human malignancies is the inhibition of cell proliferation and/or induction of apoptosis. In present experiment, we investigated the in vitro and in vivo anticancer effects and associated mechanisms of paeoniflorin (PF), isolated from the paeony root, against colorectal cancer. In vitro, cell growth assay obviously showed the inhibition of tumor cell growth in a dose-dependent manner. Flow cytometry analysis showed that PF could mainly have the cell cycle arrest at G1, which is associated with DNA damage and activation of p53/14-3-3 zeta (ζ). The pro-apoptotic effect of PF was demonstrated by Annexin V-PI staining, and activation of caspase-3 and caspase-9 by Western immunoblotting. In vivo, the results showed that positive cells of PCNA in PF and docetaxel-treated group was decreased to 30% and 15% compared with control group of tumors, respectively. But apoptosis cells in PF- and docetaxel treated groups studied by TUNEL is increased to 40 ± 1.2% and 30 ± 1.5% compared with 24 ± 2.3% in negative control, respectively. Furthermore, the efficiency of tumor-bearing mice treated by PF was superior to docetaxel in vivo. Overall, PF may be an effective chemopreventive agent against colorectal cancer HT29, and the mechanism could be mediated via an regulation of p53/14-3-3ζ.

Ellipticine cytotoxicity to cancer cell lines - a comparative study

Ellipticine is a potent antineoplastic agent exhibiting multiple mechanisms of action. This anticancer agent should be considered a pro-drug, whose pharmacological efficiency and/or genotoxic side effects are dependent on its cytochrome P450 (CYP)- and/or peroxidase-mediated activation to species forming covalent DNA adducts. Ellipticine can also act as an inhibitor or inducer of biotransformation enzymes, thereby modulating its own metabolism leading to its genotoxic and pharmacological effects. Here, a comparison of the toxicity of ellipticine to human breast adenocarcinoma MCF-7 cells, leukemia HL-60 and CCRF-CEM cells, neuroblastoma IMR-32, UKF-NB-3 and UKF-NB-4 cells and U87MG glioblastoma cells and mechanisms of its action to these cells were evaluated. Treatment of all cells tested with ellipticine resulted in inhibition of cell growth and proliferation. This effect was associated with formation of two covalent ellipticine-derived DNA adducts, identical to those formed by 13-hydroxy- and 12-hydroxyellipticine, the ellipticine metabolites generated by CYP and peroxidase enzymes, in MCF-7, HL-60, CCRF-CEM, UKF-NB-3, UKF-NB-4 and U87MG cells, but not in neuroblastoma UKF-NB-3 cells. Therefore, DNA adduct formation in most cancer cell lines tested in this comparative study might be the predominant cause of their sensitivity to ellipticine treatment, whereas other mechanisms of ellipticine action also contribute to its cytotoxicity to neuroblastoma UKF-NB-3 cells.

Cell cycle arrest and apoptosis in TP53 subtypes of bladder carcinoma cell lines treated with cisplatin and gemcitabine

Currently, the combination of cisplatin and gemcitabine is considered a standard chemotherapeutic protocol for bladder cancer. However, the mechanism by which these drugs act on tumor cells is not completely understood. The aim of the present study was to investigate the effects of these two antineoplastic drugs on the apoptotic index and cell cycle kinetics of urinary bladder transitional carcinoma cell lines with wild-type or mutant TP53 (RT4: wild type for TP53; 5637 and T24: mutated TP53). Cytotoxicity, cell survival assays, clonogenic survival assays and flow cytometric analyses for cell cycle kinetics and apoptosis detection were performed with three cell lines treated with different concentrations of cisplatin and gemcitabine. G1 cell cycle arrest was observed in the three cell lines after treatment with gemcitabine and gemcitabine plus cisplatin. A significant increase in cell death was also detected in all cell lines treated with cisplatin or gemcitabine. Lower survival rates occurred with the combined drug protocol independent of TP53 status. TP53-wild type cells (RT4) were more sensitive to apoptosis than were mutated TP53 cells when treated with cisplatin or gemcitabine. Concurrent treatment with cisplatin and gemcitabine was more effective on transitional carcinoma cell lines than either drug alone; the drug combination led to a decreased cell survival that was independent of TP53 status. Therefore, the synergy between low concentrations of cisplatin and gemcitabine may have clinical relevance, as high concentrations of each individual drug are toxic to whole organisms.

Non-genotoxic anti-neoplastic effects of ellipticine derivative NSC176327 in p53-deficient human colon carcinoma cells involve stimulation of p73

We previously performed a high-throughput screen using real-time noninvasive bioluminescence imaging of p53 transcriptional activity and identified a group of small molecules that trigger p53-like transcriptional responses in p53-deficient tumor cells. Here we further examined the anti-tumor effects of selected compounds in vitro and showed that NSC176327, a derivative of the cytotoxic plant alkaloid ellipticine, exhibited strong anti-neoplastic effect sin wild-type p53, p53-mutant or p53-deficient human colon cancer cells. NSC176327 was more potent at inhibiting tumor cell growth as compared to chemotherapeutic drugs and other ellipticine derivatives and induced cell cycle arrest and apoptosis. Surprisingly, unlike what is observed with the parent compound ellipticine, a DNA damage signaling response was not observed with NSC176327 as evidenced by lack of phosphorylated histone H2AX foci in NSC176327-treated tumor cells. NSC176327 treatment caused a significant increase in p53-activated reporter signal in HCT116, SW620 and HCT116 p53-/- cells and upregulated DR5 and p21 protein expression. NSC176327 treatment also resulted in increased p73 protein expression and knockdown of transactivating isoforms of p73 in HCT116 p53-/- cells showed significant resistance to drug treatment. These results demonstrate an important role of p73 in the anti-tumor effects of NSC176327,and suggest that a close analogue of ellipticine may act by a non-genotoxic mechanism targeting the p53/p73 pathway as compared to the original parent compound that targets the same pathway.

The mechanism of cytotoxicity and DNA adduct formation by the anticancer drug ellipticine in human neuroblastoma cells

Ellipticine is an antineoplastic agent, whose mode of action is based mainly on DNA intercalation, inhibition of topoisomerase II and formation of covalent DNA adducts mediated by cytochromes P450 and peroxidases. Here, the molecular mechanism of DNA-mediated ellipticine action in human neuroblastoma IMR-32, UKF-NB-3 and UKF-NB-4 cancer cell lines was investigated. Treatment of neuroblastoma cells with ellipticine resulted in apoptosis induction, which was verified by the appearance of DNA fragmentation, and in inhibition of cell growth. These effects were associated with formation of two covalent ellipticine-derived DNA adducts, identical to those formed by the cytochrome P450- and peroxidase-mediated ellipticine metabolites, 13-hydroxy- and 12-hydroxyellipticine. The expression of these enzymes at mRNA and protein levels and their ability to generate ellipticine-DNA adducts in neuroblastoma cells were proven, using the real-time polymerase chain reaction, Western blotting analyses and by analyzing ellipticine-DNA adducts in incubations of this drug with neuroblastoma S9 fractions, enzyme cofactors and DNA. The levels of DNA adducts correlated with toxicity of ellipticine to IMR-32 and UKF-NB-4 cells, but not with that to UKF-NB-3 cells. In addition, hypoxic cell culture conditions resulted in a decrease in ellipticine toxicity to IMR-32 and UKF-NB-4 cells and this correlated with lower levels of DNA adducts. Both these cell lines accumulated in S phase, suggesting that ellipticine-DNA adducts interfere with DNA replication. The results demonstrate that among the multiple modes of ellipticine antitumor action, formation of covalent DNA adducts by ellipticine is the predominant mechanism of cytotoxicity to IMR-32 and UKF-NB-4 neuroblastoma cells.

Resistance of cholangiocarcinoma cells to parthenolide-induced apoptosis by the excretory-secretory products of Clonorchis sinensis

Infection by Clonorchis sinensis, the Chinese or oriental liver fluke, is a significant risk factor for the development of cholangiocarcinoma, a human epithelial carcinoma of the intrahepatic bile duct. Parthenolide is a sesquiterpene lactone that has strong anticancer properties and is also known to induce apoptosis in cholangiocarcinoma cells. Many investigators have reported that excretory-secretory (ES) products of C. sinensis as well as Opisthorchis viverrini promote the development of cholangiocarcinomas. However, the intrinsic mechanism is not clearly understood. Therefore, we investigated the biological roles of the ES products in a cholangiocarcinoma cell line, HuCCT1. The ES products of C. sinensis increased proliferation of HuCCT1 cells and augmented the expression of cyclooxygenase (COX)-2. To determine whether cells treated with ES products would respond differently to parthenolide, HuCCT1 cells were treated with parthenolide alone or parthenolide after pretreatment with ES products. Cells pretreated with ES products were resistant to parthenolide-induced apoptosis. Because parthenolide has been reported to be a COX-2 inhibitor, we hypothesize that COX-2 might be a key factor that promotes resistance of cholangiocarcinoma cancer cells to parthenolide-induced apoptosis. These results suggest that chemotherapy treatment regimens in cholangiocarcinoma patients with C. sinensis infection should be modulated to account for ES products excreted by the liver fluke.

The grape and wine constituent piceatannol inhibits proliferation of human bladder cancer cells via blocking cell cycle progression and inducing Fas/membrane bound Fas ligand-mediated apoptotic pathway

Piceatannol (3,3',4,5'-Tetrahydroxy-trans-stilbene) is a polyphenol present in grapes and wine. Piceatannol is a protein kinase inhibitor that modifies multiple cellular targets exerting immunosuppressive, antileukemic, and antitumorigenic activities in several cell lines and animal models. In this study, the antiproliferative activity of piceatannol was investigated. The results showed that piceatannol inhibited the proliferation of T24 and HT1376 human bladder cancer cells by blocking cell cycle progression in the G0/G1 phase and inducing apoptosis. ELISA showed that the G0/G1 phase arrest is due to an increased in the expression of p21/WAF1. An enhancement in Fas/APO-1 and membrane-bound Fas ligand (mFasL) might be responsible for the apoptotic effect induced by piceatannol. Our study reports the novel finding, that the induction of p21/WAF1 and activity of the Fas/mFasL apoptotic system may participate in the antiproliferative activity of piceatannol in T24 and HT1376 cells.